Thermal kinetic energy recovery system for hybrid vehicle

ABSTRACT

A transmission system selectively coupled to an engine crankshaft of an internal combustion engine arranged on a vehicle includes a waste heat recovery (WHR) system, a brake assembly and a phase-change thermal heat storage system. The WHR system selectively circulates a WHR fluid in the transmission system. The brake assembly selectively couples a transmission output shaft to a drive axle. The brake assembly is configured to operate in a braking mode that retards relative rotation between the transmission output shaft and the drive axle while generating heat. The heat storage system includes a housing defining at least one cavity and a fluid transfer manifold. A phase-change material is disposed in the cavity that is configured to change phase during the braking mode. The WHR system circulates the WHR fluid through the fluid transfer manifold collecting braking heat to be used at a later time in the form of driveline power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/138,262 filed Sep. 21, 2018, which is a continuation of InternationalApplication No. PCT/US2017/023317 filed Mar. 21, 2017, which claimspriority to U.S. Provisional Application No. 62/311,170 filed on Mar.21, 2016. The disclosures of the above applications are incorporatedherein by reference.

FIELD

The present disclosure relates generally to a transmission system andrelated method for operating a vehicle having a thermal-hybrid system.

BACKGROUND

The Rankine cycle or Organic Rankine Cycle (ORC) is a power generationcycle that converts thermal energy to mechanical work. The Rankine cycleis typically used in heat engines, and accomplishes the above conversionby bringing a working substance from a higher temperature state to alower temperature state. The classical Rankine cycle is the fundamentalthermodynamic process underlying the operation of a steam engine.

The Rankine cycle typically employs individual subsystems, such as acondenser, a fluid pump, a heat exchanger such as a boiler, and anexpander turbine. The pump is frequently used to pressurize the workingfluid that is received from the condenser as a liquid rather than a gas.The pressurized liquid from the pump is heated at the heat exchanger andused to drive the expander turbine so as to convert thermal energy intomechanical work. Upon exiting the expander turbine, the working fluidreturns to the condenser where any remaining vapor is condensed.Thereafter, the condensed working fluid returns to the pump and thecycle is repeated.

A variation of the classical Rankine cycle is the organic Rankine cycle(ORC), which is named for its use of an organic, high molecular massfluid, with a liquid-vapor phase change, or boiling point, occurring ata lower temperature than the water-steam phase change. As such, in placeof water and steam of the classical Rankine cycle, the working fluid inthe ORC may be a solvent, such as n-pentane or toluene. The ORC workingfluid allows Rankine cycle heat recovery from lower temperature sourcessuch as biomass combustion, industrial wasteheat, geothermal heat, solarponds, etc. The low-temperature heat may then be converted into usefulwork such as mechanical work that can be put back into the driveline ona vehicle. In other examples it may also be converted into electricity.

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

SUMMARY

A transmission system selectively coupled to an engine crankshaft of aninternal combustion engine arranged on a vehicle includes a waste heatrecovery (WHR) system, a brake assembly and a phase-change thermal heatstorage system. The WHR system selectively circulates a WHR fluid in thetransmission system. The brake assembly selectively couples atransmission output shaft to a drive axle. The brake assembly isconfigured to operate in a braking mode that retards relative rotationbetween the transmission output shaft and the drive axle whilegenerating heat. The phase-change thermal heat storage system includes ahousing defining at least one cavity and a fluid transfer manifold. Aphase-change material is disposed in the cavity that is configured tochange phase during the braking mode. The WHR system circulates the WHRfluid through the fluid transfer manifold collecting braking heat to beused at a later time in the form of driveline power.

According to additional features, the brake assembly is an eddy currentretarder. The brake assembly comprises a magnetic portion and aconductive portion. The magnetic portion includes a group ofelectromagnetic coils arranged in a carrier. The conductive portionincludes the housing. In one example, the housing is an iron drum. Anelectromagnetic force is created between the electromagnetic coils andthe iron drum during relative rotation of the magnetic portion and theconducting portion due to eddy currents inducted in the conductiveportion through electromagnetic induction. In one example the magneticportion is configured as a rotating component while the conductiveportion remains fixed. In another arrangement, the conducting portion isconfigured as a rotating component while the magnetic portion remainsfixed. In one example, the phase-change material comprises aluminum.

According to other features a fluid transfer tube is fluidly coupledbetween the WHR system and the fluid transfer manifold. The fluidtransfer tube includes a valve disposed therein that selectively permitsthe WHR fluid circulation between the WHR system and the phase-changethermal heat storage system. Liquid waste heat recovery fluid flows intothe fluid transfer manifold. Gaseous waste heat recovery fluid flows outof the fluid transfer manifold. Heat is extracted from the phase-changethermal heat storage system. The gaseous waste heat recovery fluid isused to drive an expander of the WHR system to extract thermodynamicenergy.

A transmission system selectively coupled to an engine crankshaft of aninternal combustion engine arranged on a vehicle according to anotherexample of the present disclosure includes a waste heat recovery (WHR)system, an eddy current brake assembly, a phase-change thermal heatstorage system and a phase-change material. The WHR system selectivelycirculates a WHR fluid in the transmission system. The WHR fluid isconfigured to collect braking heat to be used subsequently by the WHRsystem in the form of mechanical work. The eddy current brake assemblyselectively couples a transmission output shaft to a drive axle. Theeddy current brake assembly is configured to operate as an electricallycontrolled mechanical brake in a braking mode to retard relativerotation between the transmission output shaft and the drive axle whilegenerating heat. The phase-change thermal heat storage system comprisesa housing defining at least one cavity and a fluid transfer manifold.The phase-change material is disposed in the at least one cavity andchanges phase during the braking mode. The phase-change materialcomprises aluminum that changes from a solid material to a moltenmaterial during the phase change.

According to additional features, the transmission system furtherincludes a fluid transfer tube that is fluidly coupled between the WHRsystem and the fluid transfer manifold. The fluid transfer tube includesa valve disposed therein that selectively permits WHR fluid circulationbetween the WHR system and the phase-change thermal heat storage system.Liquid waste heat recovery fluid flows into the fluid transfer manifold.Gaseous waste heat recovery fluid flows out of the fluid transfermanifold extracting heat from the phase-change thermal heat storagesystem. The gaseous waste heat recovery fluid is used to drive anexpander of the WHR system to extract thermodynamic energy. The wasteheat recovery fluid can comprise fluorochemical refrigerants orhalogenated hydrocarbon. The eddy current brake assembly can comprise amagnetic portion and a conductive portion. The magnetic portion caninclude a group of electromagnetic coils arranged in a carrier. Theconductive portion comprises the housing. The housing can include aniron drum. An electromagnetic force is created between theelectromagnetic coils and the iron drum during relative rotation of themagnetic portion and the conductive portion due to eddy currentsinducted in the conductive portion through electromagnetic induction.

A method of operating a transmission system that is selectively coupledto an engine crankshaft of an internal combustion engine arranged on avehicle is provided. The vehicle is braked during a braking mode with aneddy current brake assembly. The eddy current brake assembly retardsrelative rotation between a transmission output shaft and a drive axle.Heat is generated during the braking mode causing a phase-changematerial disposed in a thermal heat storage system to change phase.Waste heat recovery (WHR) fluid is circulated through a fluid transfermanifold in the thermal heat storage system. Braking heat is collectedfrom the thermal heat storage system with the WHR fluid. The WHR fluidis delivered to a WHR system.

In other features, the method includes communicating liquid WHR fluidinto the fluid transfer manifold. Gaseous WHR fluid is communicated outof the fluid transfer manifold. The gaseous WHR fluid is converted todrive an expander of the WHR system to extract thermodynamic energy.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a schematic of transmission system coupled to an engine, thetransmission system incorporating an eddy current brake assembly, aphase-change thermal heat storage system and waste heat recovery systemaccording to one example of the present disclosure; and

FIG. 2 is a schematic illustration of an exemplary vehicle thatincorporates the transmission system of FIG. 1 and is operating along aroad having a downgrade portion and an upgrade portion.

DETAILED DESCRIPTION

With initial reference to FIG. 1, transmission system constructed inaccordance to one example of the present disclosure is shown andgenerally referred to at reference 10. The transmission system 10 isselectively coupled to a fuel-controlled engine 12 (such as a dieselengine or the like), a multiple-speed, change-gear transmission 14 and amaster clutch 16 drivingly interposed between the engine 12 and an inputshaft 18 of the transmission 14. The transmission 14 may be of thecompound type comprising a main transmission section connected in serieswith a splitter and/or range-type auxiliary section. Transmissions ofthis type, especially as used with heavy duty vehicles, typically have9, 10, 12, 13, 16 or 18 forward speeds. A transmission output shaft 20extends outwardly from the transmission 14 and is ultimately drivinglyconnected with vehicle drive axles 22, usually by means of a prop shaft24.

The master clutch 16 includes a driving portion 16A connected to anengine crankshaft/flywheel 26 and a driven portion 16B coupled to thetransmission input shaft 18 and adapted to frictionally engage thedriving portion 16A. An electronic control unit (ECU) 28 is provided forreceiving input signals 30 and for processing same in accordance withpredetermined logic rules to issue command output signals to thetransmission system 10. The transmission system 10 can also include arotational speed sensor 34 for sensing rotational speed of the engine 12and providing an output signal (ES) indicative thereof, a rotationalspeed sensor 36 for sensing the rotational speed of the input shaft 18and providing an output signal (IS) indicative thereof, and a rotationalspeed sensor 38 for sensing the speed of the output shaft 20 andproviding an output signal (OS) indicative thereof. The master clutch 16may be controlled by a clutch actuator 50 responding to output signalsfrom the ECU 28.

The transmission system 10 according to the present disclosure furtherincludes an eddy current retarder or brake assembly 70, a phase-changethermal heat storage system 72 and a waste heat recovery (WHR) system74. As will become appreciated from the following discussion, thephase-change thermal heat storage system 72 provides another heat sourcethat energy can be extracted for use with the WHR system 74. Thetransmission system 10 can be implemented on a vehicle (see vehicle 200,FIG. 2) to operate the vehicle more efficiently as a thermal hybridimproving fuel economy.

The eddy current brake assembly 70 selectively couples the output shaft20 of the transmission 14 to an output shaft 76 of the brake assembly70. The output shaft 76 is drivingly coupled to the axle 22 through theprop shaft 24. In general, the eddy current brake assembly 70 can beused to brake relative rotation between the output shaft 20 of thetransmission and the output shaft 76 of the brake assembly 70, andtherefore brake the vehicle such as while the vehicle is going downhill.Braking the vehicle with the eddy current brake assembly 70 can assistand/or intermittently take the place of conventional wheel brakesimproving the longevity of the wheel brakes. The eddy current brakeassembly 70 is an electrically controlled mechanical brake. The eddycurrent brake assembly 70 generally includes a magnetic portion 80 and aconductive portion 82.

In the example shown, the magnetic portion 80 includes a group ofelectromagnetic coils 84 arranged in a carrier 86 and the conductiveportion 82 includes a housing in the form of an iron drum 88. Duringrelative rotation of the magnetic portion 80 and the conductive portion82, an electromagnetic force is created between the electromagneticcoils 84 and the iron drum 88 due to eddy currents induced in theconductive portion 82 through electromagnetic induction. It will beappreciated that while the present discussion is directed toward an eddycurrent retarder, other retarders suitable for dissipating energy suchas mechanical, hydraulic and pneumatic retarders may be employed.

In typical eddy current retarders, heat will be created in the rotatingcomponent and the rotating component moves ambient air to dissipate theheat. According to the present teachings, rather than dissipating theheat exclusively through ambient air, the iron drum 88 absorbs the heatfor use with the phase-change thermal heat storage system 72. Whenelectricity is applied to the electromagnet coils 84, the eddy currentbrake assembly 70 creates the mechanical retardation between the shafts20 and 76 while generating heat in the iron drum 88. In one example, themagnetic portion 80 can be configured as the rotating component whilethe conductive portion 82 is configured as the stationary component. Inanother example, the conductive portion 82 can be configured as therotating component while the magnetic portion 80 is configured as thestationary component. While not shown, slip rings or otherconfigurations can be incorporated to permit electrical and/or fluidtransfer into the rotating component.

The phase-change thermal heat storage system 72 will be furtherdescribed. The phase-change thermal heat storage system 72 generallycomprises at least one cavity 100 and a fluid transfer manifold 102. Thecavity 100 contains a phase-change material 110 that has a high capacityfor absorbing heat such as aluminum. Other materials may be used suchas, but not limited to, waxes. As the iron drum 88 absorbs heat, thephase-change material 110 melts (in this example into molten aluminum)and absorbs energy. The fluid transfer manifold 102 can include at leastone and preferably a plurality of fluid conduits 120 that communicatewaste heat recovery fluid between the iron drum 88 and the WHR system 74through a fluid transfer tube 130.

The fluid transfer tube 130 can incorporate a valve 132 for selectivelypermitting fluid communication between the WHR system 74 and the fluidtransfer manifold 102. It is contemplated that a controller such as theECU 28 can communicate a signal to the valve 132 to open and close thevalve 132 as desired. It is further appreciated that the configurationof the fluid transfer manifold 102 and the fluid transfer tube 130 shownin FIG. 1 is merely exemplary and other configurations are contemplated.

When the vehicle is operating in a powering mode, the WHR system 74 isoperated such that the waste heat recovery fluid in the fluid conduits120 is circulated through the fluid transfer manifold 102 collecting thebraking heat to be used at a later time in the form of driveline power.The waste heat recovery fluid can comprise any suitable fluid such asfluorochemical refrigerants or halogenated hydrocarbon. Other fluidssuch as, but not limited to ammonia or alcohol may be used. In thisregard, the thermal energy can be extracted to be converted back to workat a later time such as during the drive cycle when propulsive energy isrequired. Energy is absorbed by creating heat in the iron drum 88 andenergy is desorbed by circulating the waste heat recovery fluid betweenthe WRH system 74 and the manifold 102 for later converting that energyback to mechanical work.

While the WHR system 74 is shown circulating waste heat recovery fluidwith the phase-change thermal heat storage system 72, the WHR system 74can be configured to additionally circulate heat with other systems ofthe vehicle such as an exhaust gas recirculation (EGR) unit, an exhaustpipe heat exchanger and/or the charge air coolant system. In thisregard, the WHR system 74 can be used concurrently with otherconventional vehicle systems known to provide suitable heat sources.

With additional reference now to FIG. 2, an exemplary method ofoperating the transmission system 10 will be described. The transmissionsystem 10 can be incorporated into vehicle 200. As the vehicle 200travels along a downgrade portion of road 210, supplemental vehiclespeed retardation is achieved by activating the eddy current brakeassembly 70. Again, as the electromagnetic coils 84 are energized, anelectromagnetic force is created between the electromagnetic coils 84and the iron drum slowing relative rotation of the shafts 20 and 76while creating heat in the phase-change thermal heat storage system 72.Once the heat of the iron drum 88 reaches a phase change temperature ofthe phase change material 110, the phase change material 110 melts.

After travelling down the road downgrade 210, the vehicle 200 travelsalong a generally zero grade portion of road 212 and approaches anupgrade portion of road 214. At this time, the valve 132 is openedallowing the liquid waste heat recovery fluid to flow into the manifold102 and gaseous waste heat recovery fluid to flow out of the manifold102 extracting the heat from the phase-change thermal heat storagesystem 72. The gaseous waste heat recovery fluid is used to drive anexpander of the WHR system 74 to extract thermodynamic energy.

The foregoing description of the examples has been provided for purposesof illustration and description. It is not intended to be exhaustive orto limit the disclosure. Individual elements or features of a particularexample are generally not limited to that particular example, but, whereapplicable, are interchangeable and can be used in a selected example,even if not specifically shown or described. The same may also be variedin many ways. Such variations are not to be regarded as a departure fromthe disclosure, and all such modifications are intended to be includedwithin the scope of the disclosure.

What is claimed is:
 1. A transmission system selectively coupled to anengine crankshaft of an internal combustion engine arranged on avehicle, the transmission system comprising: a waste heat recovery (WHR)system that selectively circulates a WHR fluid in the transmissionsystem; a brake assembly that selectively couples a transmission outputshaft to a drive axle, the brake assembly configured to operate in abraking mode that retards relative rotation between the transmissionoutput shaft and the drive axle while generating heat; and aphase-change thermal heat storage system having a phase-change materialdisposed therein, wherein the phase-change material is configured tochange phase during the braking mode, the WHR system collecting brakingheat to be used at a later time in the form of driveline power.
 2. Thetransmission system of claim 1 wherein the brake assembly is an eddycurrent retarder.
 3. The transmission system of claim 2 wherein thebrake assembly comprises a magnetic portion and a conductive portion. 4.The transmission system of claim 3 wherein the magnetic portion includesa group of electromagnetic coils arranged in a carrier and theconductive portion comprises the housing.
 5. The transmission system ofclaim 4 wherein the housing comprises an iron drum.
 6. The transmissionsystem of claim 5 wherein during relative rotation of the magneticportion and the conductive portion, an electromagnetic force is createdbetween the electromagnetic coils and the iron drum due to eddy currentsinducted in the conductive portion through electromagnetic induction. 7.The transmission system of claim 6 wherein the magnetic portion isconfigured as a rotating component while the conductive portion remainsfixed.
 8. The transmission system of claim 6 wherein the conductiveportion is configured as a rotating component while the magnetic portionremains fixed.
 9. The transmission system of claim 1 wherein thephase-change material comprises aluminum.
 10. The transmission system ofclaim 1, wherein the phase-change thermal heat storage system comprisesa housing defining at least one cavity and a fluid transfer manifold,wherein the phase-change material is disposed in the cavity, wherein thetransmission system further comprises a fluid transfer tube fluidlycoupled between the WHR system and the fluid transfer manifold, whereinthe fluid transfer tube includes a valve disposed therein thatselectively permits the WHR fluid circulation between the WHR system andthe phase-change thermal heat storage system.
 11. The transmissionsystem of claim 10 wherein liquid waste heat recovery fluid flows intothe fluid transfer manifold and gaseous waste heat recovery fluid flowout of the fluid transfer manifold extracting the heat from thephase-change thermal heat storage system, the gaseous waste heatrecovery fluid used to drive an expander of the WHR system to extractthermodynamic energy.
 12. A transmission system selectively coupled toan engine crankshaft of an internal combustion engine arranged on avehicle, the transmission system comprising: a waste heat recovery (WHR)system that selectively circulates a WHR fluid in the transmissionsystem, the WHR fluid configured to collect braking heat to be usedsubsequently by the WHR system in the form of mechanical work; an eddycurrent brake assembly that selectively couples a transmission outputshaft to a drive axle, the eddy current brake assembly configured tooperate as an electrically controlled mechanical brake in a braking modeto retard relative rotation between the transmission output shaft andthe drive axle while generating heat; a phase-change thermal heatstorage system; and a phase-change material disposed in the phase-changethermal heat storage system that changes phase during the braking mode,the phase-change material comprising aluminum that changes from a solidmaterial to a molten material during the phase change.
 13. Thetransmission system of claim 12, further comprising a fluid transfertube fluidly coupled between the WHR system and the fluid transfermanifold, wherein the fluid transfer tube includes a valve disposedtherein that selectively permits the WHR fluid circulation between theWHR system and the phase-change thermal heat storage system.
 14. Thetransmission system of claim 13 wherein liquid waste heat recovery fluidflows into the fluid transfer manifold and gaseous waste heat recoveryfluid flow out of the fluid transfer manifold extracting the heat fromthe phase-change thermal heat storage system, the gaseous waste heatrecovery fluid used to drive an expander of the WHR system to extractthermodynamic energy.
 15. The transmission system of claim 14 whereinthe waste heat recovery fluid comprises a fluorochemical refrigerant.16. The transmission system of claim 12 wherein the eddy current brakeassembly comprises a magnetic portion and a conductive portion, themagnetic portion including a group of electromagnetic coils arranged ina carrier, the conductive portion comprises the housing.
 17. Thetransmission system of claim 16 wherein the housing comprises an irondrum.
 18. The transmission system of claim 17 wherein during relativerotation of the magnetic portion and the conductive portion, anelectromagnetic force is created between the electromagnetic coils andthe iron drum due to eddy currents inducted in the conductive portionthrough electromagnetic induction.
 19. A method of operating atransmission system that is selectively coupled to an engine crankshaftof an internal combustion engine arranged on a vehicle, the methodcomprising: braking the vehicle during a braking mode with an eddycurrent brake assembly, the eddy current brake assembly retardingrelative rotation between a transmission output shaft and a drive axle;generating heat during the braking mode causing a phase-change materialdisposed in a thermal heat storage system to change phase; circulatingwaste heat recovery (WHR) fluid through the thermal heat storage system;collecting braking heat from the thermal heat storage system with theWHR fluid; and delivering the WHR fluid to a WHR system.
 20. The methodof claim 19, further comprising: communicating liquid WHR fluid into afluid transfer manifold in the thermal heat storage system;communicating gaseous WHR fluid out of the fluid transfer manifold; andconverting the gaseous WHR fluid to drive an expander of the WHR systemto extract thermodynamic energy.